1. Field of the Invention
The present invention relates to a laser apparatus comprising plural beam emitting ends serving as a laser beam output port.
2. Related Background Art
Today, processing technology employing a pulsed laser beam (obtained by pulsing and repeatedly outputting a laser beam at a predetermined cycle) is attracting attention, and demands for a high output laser apparatus are increasing in the fields for processing and medical use. There is an optical fiber laser as a laser apparatus that is particularly attracting attention among the seed laser apparatuses. This optical fiber laser adopts, as the light amplifying medium, an amplification optical fiber in which rare earth elements such as Yb (ytterbium), Er (erbium, Tm (thulium) and the like are doped. When pumping light is supplied into this amplification optical fiber, the seed light propagating in the amplification optical fiber is amplified. Consequently, high power amplified light is outputted from the amplification optical fiber or, by performing laser oscillation with a resonator structure, laser beam is outputted from the amplification optical fiber. Some advantages of the optical fiber laser are, for example, the handling of the laser beam is easy since it is confined in the optical fiber, and large-scale cooling equipment is not required since the thermal radiation characteristics are favorable.
As described above, a rare earth-doped optical fiber is used as the optical fiber laser, and in particular a Yb-doped optical fiber is broadly used as the amplification optical fiber for high power output since conversion efficiency of Yb is high among the doped rare earths. Yb is pumped by using pumping light as with the other rare earth elements. Meanwhile, the pumping light that could not be absorbed in the amplification optical fiber is emitted from the other end of the amplification optical fiber.
As the configuration of a optical fiber laser, for example, when a resonator structure using a Fiber Bragg Grating (FBG) or a reflective mirror on either end, pulse modulation is performed by disposing an optical switch or an Acoustic Optical Modulator (AOM) in the resonator. Moreover, the MOPA (Master Oscillator Power Amplifier)-type optical fiber laser as described in Japanese Patent Application Laid-Open No. 2007-042981 performs pulse modulation by directly or externally modulating the seed light source (light-emitting device) for outputting the light to be amplified, and obtains a high power output beam by amplifying the obtained light pulse.